In general, a valve is placed in a channel of a fluid and used for controlling the flow of the fluid. As an example of the most basic control for opening or closing such a valve, there is an operator's manual control. Besides, various kinds of control based on an electric signal have been known.
The valve opened or closed by force based on the foregoing operator or electricity has been developed to have various forms and structures. Furthermore, Korean patent No. 10-1709667 has proposed a valve assembly that is opened or closed by not the external force but its own inclination. However, there are disadvantages to such a valve assembly that may have complicated structures as compared with functions and may have a problem with exact operation due to internal pressure of a valve body.